Electric heating device



Patented Jan. 1l, 1927.

UNITED STATES PATENT OFFICE.

JAMES H. REICHART, OF MUNCIE, INDIANA, ASSIGNOR TO JACOB L. MOORE, OF MUNCIE, INDIANA.

ELECTRIC HEATING DEVICE.

Application filed July 31, 1924. Serial No. 729,216.

This invention relates to electric heating devices and has for its object the provision of a new and improved type, design, and arrangement of heating disk or hot plate whereby the coils are more closely concentra-ted and whereby plural coils or circuits are arranged in a minimum superiicial area. In certain electric cooking apparatus it is customary to locate the resist ance wire in grooves in a porcelain plate or disk, the wire being first coiled to helical shape. For some kinds of cooking, as in heating small dishes or coffee percolators, it is desirable to have a small, concentrated heated surface; for other uses a wider distribution is desired, together with a facility for increasing or decreasing the total heat energy supplied. To accomplish these objects with a minimum of complexity, eX- pense and heat-loss is the main object of this invention; another object is the provision of a resistance heating unit wherein the maximum possible proportion of the heat generated shall be applied to the vessel being heated and the smallest proportion absorbed by the supporting device or otherwise wasted; while further objects and advantages will appear as this description proceeds.

In the drawings accompanying and forming a part of the -application I have shown certain preferred embodiments of my invention. Figs. l, 2, and 3 are plan views of different designs of hot plate, and Fig. i in a sectional view on the line lwli of Figs. l and 2.

Describing the parts by reference chan' gammadion or fylfot or it may be considered as a star with each of its rays elongated and inclined so as to overlap the adjacent ray. I have shown a five pointed iigure although I do not restrict myself thereto as the number may be increased or decreased. This produces a symmetrical arrangement and affords a maximum length of groove in the minimum area.

lVhen plural grooves are employed the inner groove is made of the shape shown in Fig. 3 (except that I do not limit myself to the iive pointed figure), and is surrounded by an outer symmetrical groove, having arcuate portions et and internal projections lying in the spaces deiined between the convolutions of the internal groove. These internal projections can either take the form of plain loops 5 as shown in Fig. 2 or of longer loops 6 as sho-wn in Fig. l, the same being inclined to the radius in the latter case so as to parallel the corresponding portions of the internal groove. In either case the space between the two branches of the loops 5 and 6 can be formed with apertures 7 for the reception of screws or securing means.

The resistance wire can be fastened in place in any suitable manner as by wire loops S passing through holes 9 in the disk or plate and having their ends bent laterally as shown in Fig. 4.

It will be understood that additional external grooves can be employed if desired or other shapes of plate, or other modes of fastening the plate or the wires, and other changes made and that I limit myself only as defined in my claims and as required by the prior state of the art.

Having thus described my invent-ion, what I claim is:

l. An electric heating device comprising an insulating support and a resistance heating element carried thereby so arranged as 90 to surround a center and having a plurality of outwardly projecting loops each defiected laterally in the same angular direction so that each loop overlaps the next.

2. An electric heating device comprising an insulating support and a pair of resistance heating elements carried thereby, one element being of involute t'orni surrounding and symmetrical about a center and having a plurality ot' outwardly projecting loops separated by inwardly extending indentations, the extremities ot said loops being deflected laterally in the saine angular direction so that each overlaps the next, the other element surrounding the irst element and having portions which bridge the extremities of said loops and also having internal loops lying in the spaces defined between said irst loops.

In testimony whereof, I hereunto atti); my

signature.

VJAMES H. REICHRT. 

